This invention relates to coating apparatus wherein a solid applicator roll contacts the work, with the applicator roll being movable between operative positions and open positions. More particularly, this invention relates to a glue applicator of the type used to apply liquid glue to sheet material, such as to blanks which are ultimately formed into paper boxes, with the blanks being processed between rotatable rolls, with certain ones of the rolls being locked into their operative positions during the operation of the glue applicator and movable from their locked positions to opened positions for maintenance when the operation of the glue applicator has been terminated.
Prior glue applicator equipment has been developed for the purpose of feeding sheets of material in sequence to a series of processing stations and coating the sheet material with glue and other liquids at one of the processing stations. As illustrated in my U.S. Pat. No. 4,119,057, these machines typically include equipment for picking off the end sheet from a stack of sheet material, feeding the sheet along a path generally parallel to the plane of the sheet material past a rotating cylindrical glue applicator roll, and then to various subsequent work stations. The glue applicator roll usually continuously rotates in contact with a wetting roll which is partially submerged in the body of liquid glue or other liquid.
The equipment is constructed so that its various processing rolls can be separated from one another, from their usual operating positions to an open position. This permits the operator to extract misaligned sheet material and other items from between the rolls when the equipment malfunctions, and to clean or otherwise maintain the equipment. Certain ones of the rolls are mounted at their ends in rotatable relationship with respect to a stationary frame while other ones of the rolls are mounted at their ends in rotatable relationship with respect to a movable frame. When the movable frame is in its operating position, it is desirable to lock it in its operating position so that various vibrations encountered by the equipment during its normal operating function do not tend to jar the rolls apart and cause the rolls to improperly feed the sheet material.
The prior art equipment has utilized various lock pin arrangements where, for example, a lock pin is inserted through aligned openings of the movable frame and the stationary frame when the movable frame is in its operating position. While the prior art lock pin arrangement assists to some extent in reducing the effect of vibration of the movable frame and its rolls, extended use of the equipment and the continuous vibration of the equipment eventually causes the lock pin and its holes to wear, resulting in a loose connection and therefore permitting increased vibrations between the movable frame and the stationary frame. This increases the likelihood of malfunction of the equipment.